[DoctorBeny]

You will burn about the same number of calories if you break it up into 2 workouts or do it in one workout. However, one of the benefits of cardio exercise is heart health. The longer you do the exercise, the better it is for your health. Breaking up the exercise into 2 short segments is not as good as a single longer segment.

I would recommend that instead of picking a particular distance, that you plan to pedal for a certain amount of time (say 20 minutes). Then, gradually increase your time and intensity. Over time, you'll burn calories and increase your heart health.

Brian